Lawn edger

ABSTRACT

A powered lawn edger which is steerable by a walking operator in the manner of a wheelbarrow. The edger has a Y-shaped frame including a pair of handles each with handlegrips. A power unit is mounted on the frame between the handlegrips and a ground engaging wheel. A cutting blade is rotatable about an output shaft of a gear box which is powered from the power unit via a centrifugal clutch having a brake. A debris deflector is mounted on the axle of the wheel. An adjustment mechanism is provided to adjust the height of the cutting blade relative to the ground. The height of the debris deflector relative to the ground remains unchanged when the height of the cutting blade is adjusted.

The present invention relates to powered lawn edgers. In particular, thepresent invention relates to a safe, compact, streamlined, and extremelymanoeuvrable powered lawn edger which is steerable with both hands inthe manner of a wheel barrow.

Hitherto, powered lawn edgers have been able to be divided into severalcategories. The first is a multi-wheeled carriage which is selfsupporting on its wheels and which is pushed along its intended path.The best known member of this class is essentially a conventionaldomestic lawn mower type but with a cutting element rotating in avertical plane. Another category is a hand held device which does notnormally have any ground engaging wheels and which is carried by theoperator. The best known of these devices are the various types of brushcutter or trimming devices.

The brush cutter type of device generally includes a nylon filament as acutting element. This cutting element is attached to a cutter head whichis set at one (lower) end of a long drive shaft. The drive shaft issupported by the operator at an angle of approximately 45° to thehorizontal. The shaft has an engine at its other (upper) end with theengine mostly situated behind the operator and in some other casesbeside the operator. The cutter head rotates about a substantiallyhorizontal plane in normal use and is intended, for example, to trimgrass growing adjacent tree trunks, to mow grass in small and/or awkwardareas, and the like. Therefore in order to trim the edge of a lawnadjacent a footpath, for example, it is necessary for such an apparatusto be completely carried whilst being twisted by approximately 90° aboutits longitudinal axis in order to bring the plane in which the cuttingdevice rotates into an inclined, but nearly vertical, position. Thisplaces the complete apparatus in an extremely out of balance positionand this particularly awkward motion requires an awkward operatorposition. Also a particularly awkward crab-like walking motion isrequired during use. Indeed most operators walk backwards, and sidewayssimultaneously. Therefore it is both difficult and tiring to execute.

As a consequence, any health problem of the operator, such as commonback ache, can be exacerbated by this stooped and unnatural position.The tiredness of the operator is further increased by the need toactually carry, and therefore support the entire weight of, the deviceduring its operation. Furthermore, unlike a blade of a lawn edger, thenylon filament of such trimming devices does not cut into the soilsurface and therefore does not give a clean cut or neat edge.

Other prior art variations include lawn edge cutting attachments forsuch brush cutter devices. These include those in which the rotatableimplement rotates in a substantially vertical plane. Typically thesedevices use a short, high peripheral speed, cutter blade whichpenetrates the soil surface to edge the lawn. However, these devices,with the engine behind or beside the operator, still suffer from thefundamental disadvantage that the entire weight of the apparatus iscarried by the operator at an angle of about 45 degrees away from thecutter blade axis. Furthermore, to make the cutter blade penetrate thesoil surface, the operator has to stoop further in order to force theentire cutting head downwardly.

These prior art brush cutter type devices also only have a safety guardparallel to (and positioned above) the cutting head for protectionduring normal grass cutting when the head is cutting horizontally. As aresult, when the apparatus is manoeuvred so that the cutting head isrotating in a near vertical plane for lawn edging, then this exposes thecutting head and allows any hidden object such as stones, sand or evenforeign objects such as nails from previous building debris etc, to bethrown up out of the grass at speed. Of course, such objects then becomehigh speed projectiles which are dangerous to both operator and tobystanders, be they distant or close by.

It is also known for some such prior art brush cutter devices to befitted with a small roller attached to the device near the cutter head.These devices still have their engine alongside, or behind, the operatorso the majority of the weight is still supported by the operator withthe same generally awkward stance and movement as described above. Onehand of the operator carries the majority of weight whilst the otherhand of the operator holds down, or forces down, the cutter head. Againthis causes stooping which exacerbates any back problem. Back problemsare a major source of health insurance injury claim and are a majorsource of injury for manual labourers.

Various prior art devices in the form of a wheeled dolly have beenproposed in order to support such brushcutter devices. The followingU.S. patents are typical of such devices, U.S. Pat. No. 4,182,100(Letter); U.S. Pat. No. 4,442,659 (Enbusk); U.S. Pat. No. 4,531,350(Huthmacher); U.S. Pat. No. 4,803,831 (Carmine); U.S. Pat. No. 4,879,869(Buckendorf); U.S. Pat. No. 4,894,916 (Nimz); U.S. Pat. No. 4,922,694(Emoto); U.S. Pat. No. 4,936,886 (Quillen); U.S. Pat. No. 5,029,435(Buchanan); and U.S. Pat. No. 5,095,687 (Andrew).

Similarly, two U.S. Pat. No. 4,364,435 and U.S. Pat. No. Re 32,266, bothto Tuggle disclose a single, small diameter, roller support for abrushcutter device, and an earlier U.S. Pat. No. 4,286,675 also toTuggle discloses a single wheel support for a brushcutter. In thesethree patents, the weight of the engine of the brushcutter is supportedby a handle connected to that engine whilst an outrigger handle isprovided for stability. Again, because the heaviest component of thedevice, namely the engine, is directly supported by a handle held by theoperator, the operator awkwardly supports most of the weight of thedevice with one bent arm. The other arm is outstretched and holds theoutrigger handle.

A further problem to be considered is the expected restrictions to beplaced on small two-stroke (two-cycle) engines because of the pollutionsuch engines create over and above that created by four-stroke engines.As a consequence, the light weight two stroke power units currently usedin brushcutters and similar devices are likely to be banned in somejurisdictions in future for anti-pollution reasons. The engineeringresult of this is that commercially acceptable power units arehenceforth likely to be restricted to four-stroke internal combustionengines and electric motors, both of which are substantially heavierthan two-stroke engines. It follows therefore that in future those brushcutters in which the operator carries the weight of the apparatus willbecome eventually impractical.

The wheeled carriage class of prior art lawn edger typically has three(or sometimes four) wheels arranged so as to enable the edger to be freestanding, with upstanding handles, and also self supporting on itswheels. These wheels hold the device so that the rotatable cuttersrotate in a substantially vertical plane. The device is pushed in amanner analogous to that of a lawn mower. Because these self supporting3 and 4 wheeled carrriage grass edgers have a long wheel base to selfsupport the apparatus, when pushed (forward) their natural track isstraight and therefore to edge around a curve is very difficult with theoperator having to "bounce", or reciprocate, or drag, the apparatusaround, to try and approximate to the curve which the non-steerablecarriage wheels will not follow. Also the weight of these prior artdevices is distributed amongst the three or four carriage wheels so thecutter blade does not have a great deal of weight (downwardly directforce) applied to it. This is due to the long leverage distance betweenthe cutter blade axis and the rear wheels (which constitute the pivotpoint when reaction forces are applied to the blade when the bladestrikes hard ground). As a consequence, the blade pushes the front ofthe machine upwardly when blade strikes hard ground. As a result, inhard soils this weight distribution and reaction force can cause thecarriage to "bounce" and be less stable.

In addition, because of the wide side to side spacing between the wheelsof the free standing carriage, necessary to make the carriage stable, itis difficult to tilt the edger so as to move the cutting blade out ofthe vertical the plane in which it rotates. Typical of these are priorart devices are those disclosed in the following U.S. Pat. No. 2,847,813(Hanson); U.S. Pat. No. 3,130,793 (Allegretti); and U.S. Pat. No.3,734,196 (Mangum).

For a prior art edger having a three (or four) wheeled carriage, it ispossible for the edger to be tilted sideways in one direction. This isthe direction in which the wheel(s) furthest from the cutter is lifted.This tilts the lower edge of the "disc" in which the blades rotatetowards the lifted wheel. This is generally non-effective since themovement of the "disc" in which the blades rotate is towards the wheels.In order to tilt the "disc" in the other direction, it is necessary toraise the engine and so the cutter blade is raised upwardly, away andwell clear from the ground surface. This is caused by the spacingbetween the cutter blade and the remaining ground engaging wheel(s). Theraised "disc" means that the cutter blade(s) do not come into contactwith the material to be cut. U.S. Pat. No. 2,847,813 (Hanson); U.S. Pat.No. 3,130,793 (Allegretti) and U.S. Pat. No. 3,734,196 (Mangum); andWEEDEATER (Registered Trade Mark) gasoline model GE21 as sold byELECTROLUX exemplify this art. This inability to operatively tilt thedevice creates substantial problems particularly in edging against wallsand fences and in also in edging adjacent curbs and gutters.

In order to overcome this problem it is known to provide some models ofsuch wheeled carriage edgers, and these can be categorised as heavy dutyedgers, with a swivel mechanism to enable the cutting blade(s) to betilted out of the vertical plane. Generally such swivel mechanisms takethe form of a tiltable axis of rotation of the cutter, and a V-beltdrive which is able to accommodate the necessary twisting requiredwhilst still transmitting power. The power unit remains untilted. Whilstsuch arrangements are functional, the devices are heavier, morecomplicated and more expensive. In addition, the (often exposed) V-beltdrives are dangerous.

Such prior art heavy duty edgers also require the operator to pull orpush a locking device, and/or twist or pull or push a lever, so that theplane of the cutter is tilted and locked at its desired position. Thisis an operation that is not fast or simple, and for old or less athleticoperators in domestic situations can be difficult to execute. These beltdrive edgers also are provided with an adjustment mechanism to tensionthe belt drive. Thus the motor and cutter blade shaft are not at a fixeddistance from each other.

Examples of prior art wheeled carriage devices which have attempted todeal with this problem include U.S. Pat. No. 2,680,945 (Reed); U.S. Pat.No. 2,791,875 (Faas); U.S. Pat. No. 2,885,742 (Cooper); U.S. Pat. No.2,930,176 (Lindell); U.S. Pat. No. 3,090,166 (Dykes); U.S. Pat. No.3,193,996 (Wellborn); U.S. Pat. No. 3,490,213 (Pinto); U.S. Pat. No.3,743,028 (McCloud); U.S. Pat. No. 4,962,631 (Braun); U.S. Pat. No.5,156,217 (Hirata); and U.S. Pat. No. 5,165,485 (Fujikawa). Thecommercially available MASPORT (Registered Trade Mark) model 6002 DLXalso has a blade tilting arrangement. All of these "heavy duty" wheelededgers are heavy and bulky; difficult to transport, cannot fit into aboot or trunk of even a large car, and require a great deal of room forstorage.

Another example of a prior art device in which the cutting blades areable to be tilted out of the vertical plane is provided by U.S. Pat. No.2,970,419 (Lieberman). This device enables a cut to be achieved both ina horizontal plane and in a vertical plane. When cutting in a horizontalplane the device is supported by a pair of wheels 40 and when cutting ina vertical plane the device is supported by a roller 54. U.S. Pat. No.2,672,002 (Nelson) discloses a somewhat similar device which, whencutting in the vertical plane is supported by single wheel 15 in frontof the cutter blade, but when cutting in the horizontal plane Issupported by a skid bar 28. Because of the skid bar 28 it is necessaryto "shove or push" the device in the direction of the bar 29 utilising ahandle 31 which has "any desirable cross-head" and therefore issubstantially T-shaped in configuration.

U.S. Pat. No. 2,621,463 (Skillman) discloses a similar arrangement inwhich the device is supported in both cutting actions by a roller 11having a substantial axial extent. Again, the cutting blades are able tobe pivoted so as to cut in either a horizontal plane or a verticalplane. U.S. Pat. No. 2,632,990 (Stricken) discloses a single wheeledcarriage device with a free standing and upstanding handle. The carriagehas supporting shoes or skids 20 to maintain the carriage upright in therest position. The device is able to cut either vertically orhorizontally. When cutting horizontally, the cutter blade is able to bepivoted in a horizontal plane about a vertical axis on a cutter supportarm. When cutting vertically the line of cut is substantially offsetfrom the center line of the machine. A complex belt drive is required.

U.S. Pat. No. 2,618,919 (Hutchens) also discloses a single wheeledcarriage arrangement with both a horizontally cutting trimmer blade 11and a vertically cutting cutter blade 19. Each of these blades is ableto be swivelled to a tilted position and independently operated so thatsimultaneous inclined cuts, or two simultaneous horizontal cuts are ableto be achieved. This device is supported by a single wheel and a pair ofshort legs 31. The device has a conventional free standing andupstanding handle 29 which is presumed to be the then conventionalT-shaped lawnmower handle. Each cutting blade, in order to swivel, ismounted on an outrigger journal and is at a considerable horizontaldistance from the wheel when the blade is in the vertical position.Except for the handle arrangement, the device is of very broaddimensions with the cutters extending a long way forward of the singlewheel. This single wheel is placed approximately midway front to rearand approximately on the centerline of this carriage device toconstitute both a front to rear and a left to right pivot point.However, the carriage has substantial masses located at some distancefrom the pivot or balance point. As a result, the device is unwieldly;being difficult to balance and therefore difficult to use.

In a follow-up invention, the same inventor in U.S. Pat. No. 2,719,398discloses basically the same machine as previously but with only asingle cutter rotating in a swivel tilted position or a vertical plane.Again, the cutter is mounted on a swivel outrigger journal which whenthe blade is vertically aligned is spaced sideways by a substantialhorizontal distance from the wheel. This swivel arrangement of thecutter is necessary to enable any effective tilted cut to be achieved asthe wide dimensions and low clearance of the frame of the carriagedevice prevent laterally tilted cutting action. As before with hisearlier device, tilted cuts can only be achieved by swivelling theoutrigger arm of the blade. For this reason a separate cutter blade tiltmechanism is provided to enable effective edging with the tilted blade,for example for edging against a wall. This single wheel device is againpushed by a conventional free standing and upstanding single shaftmower-type handle 20 which is again presumed to have a T-shaped upperend as was then conventional.

U.S. Pat. No. 2,478,813 (Esleck) also discloses a single wheel carriagedevice with a conventional free standing and upstanding T-shaped handle7 with a pair of closely spaced hand grips 17. In this lawn edger theaxes of the single supporting wheel 14 and the cutter blades 29 arealigned or coincident. Similarly, U.S. Pat. No. 2,707,859 (Walker) alsodiscloses a device having a vertical cutting disc supported by a singlewheel 12 and manipulated by a conventional handle 14 having a cross headhandle 15 with two closely spaced handgrips. The wheel 12 is in front ofthe cutter.

U.S. Pat. No. 2,708,335 (Newton) also discloses a single wheel devicewhich in this instance is able to cut both horizontally and vertically.The single wheel supports the motor and cutter blade while cuttingvertically. It is not clear how the device is supported duringhorizontal cutting as illustrated in FIG. 5. In this device the handle27 consists of a single bent tube and therefore it would be necessaryfor the operator to keep a very firm grip on the handle in order toprevent the device twisting or tilting whilst cutting vertically. U.S.Pat. No. 2,653,381 (Rooke) discloses a similar device with a rod-likehandle 27 which again has a single grip 43. A roller 36 supports thedevice whilst trimming vertically and the device appears to be supportedby skids whilst cutting horizontally.

U.S. Pat. No. 4,033,098 (Green) discloses a device for cuttinghorizontally which has a single wheel 11 and a pair of spaced aparthandles 33. As seen in FIG. 5, in order to cut grass adjacent a wall 42,it is necessary for the handles 23 to be released, then twisted to oneside and then secured in that position in order that the operator's handnot be scraped during the passage along the wall 42. Furthermore,because the large motor 12 is mounted forwardly of the wheel 11, thecenter of gravity of the device is forward of the wheel 11. Therefore,in operation it is necessary for the handles 33 to be forced downwardlyin order to maintain the correct cutting height. If, during operation,the handles 33 are inadvertently released, then the cutting elements 28immediately impact with the ground, which is extremely dangerous.

Another single wheeled device in which the center of gravity is forwardof the single wheel is that disclosed in Australian Patent No. 107,917(Collins and Henderson). This device has a cutting disc 4 which normallyrotates in a horizontal plane above a pair of skids 16 which assist tosupport the weight of the device. The weight of the cutting arrangementmeans that the center of gravity of the device is forward of the wheel2, notwithstanding that the engine 3 is mounted above, but just behind,the wheel 2. Again, in operation it is necessary for the operator topush down on the handles 13 in order to relieve the weight on the skids16.

U.S. Pat. No. 4,845,929 (Kawasaki) again discloses a device for cuttinghorizontally (rather than vertical edging) in which a pair of wheels ispositioned inside a dome-shaped cutting disc. The wheels are pivotableabout a vertical axis in order to permit cutting in differentdirections. In the second embodiment of FIGS. 19-23, the trimmer issupported by a pair of running wheels 8, and a skid 170 (column 12, line37) but designated 156 In FIG. 20. This indicates that the center ofgravity of the device is forward of the wheels 8 and therefore the guidehandles 16 have to be depressed in order to operate the device.

U.S. Pat. No. 3,168,147 (Peters) discloses a single wheel carriagedevice with free standing and upstanding handles. The offset handlesenable the operator to overcome the tendency of the out of balancedevice to tip laterally. The cutter blade 11 is on an outrigger journalwhich is offset to one side. The foot 24 stops both lateral tilting andrearward tilting. The apparatus is unstable and difficult to useespecially considering the awkward situation of the operator. This isbecause of the geometry of the apparatus including the considerablehorizontal distance between the wheel centerline and the cutter blade.Thus, it is impractical to try to laterally tilt the apparatus for atilted cut. Further, the operator is required to simultaneously push andhold forward (against spring pressure) the pad 16. This holds down thepivoted journal arm for the blade, to set the blade's cutting position.As well as having to overcome the spring pressure, the operator also hasto have enough thumb strength to stop the blade "bouncing" out of theground. This applies particularly if the ground is hard, or worse still,if the blade hits a solid object.

U.S. Pat. No. 3,533,223 (Gunn) discloses a sand trap edger withfloatable blade carrying arm supported by a second wheel. The cutterblade is a substantial horizontal distance from the wheel centerline andmounted in an outrigger fashion. U.S. Pat. No. 2,706,941 (Swanson)discloses a single wheel device but has the wheel forward of the cutter.The operator is said to walk backwards with base plate 10 sliding overthe grass surface.

A further problem to be considered is the present and future mandatorysafety requirements in some jurisdictions whereby it is, or will be,required that the blade of the lawn edger must come to a complete stopwithin a given time after the operator releases the engine throttle.This is similar to the present regulations applying to rotory lawnmowers in these jurisdictions. The specified amount of time varies fromone jurisdiction to another but is typically as short a time as threeseconds.

U.S. Pat. No. 4,984,417 (Braun et al) is an example of a (belt driven)lawn edger with a safety brake arrangement fitted.

As a consequence of this regulatory environment, lawn edgers whichinclude this type of safety requirement of stopping or braking the bladewithin a given time, will have an additional cost in the cost ofmanufacturing such edgers.

Such edgers, especially those with belt drives, normally have afour-stroke engine with an output shaft speed in vicinity of 1500-2000rpm which is approximately the same rotational speed desired for thecutter blade. As a consequence the gear ratio of the belt drive istypically in the range of from 1:1 to 1.25:1 and almost never exceeds1.5:1.

The consequence of this gear ratio is that when the clutch mechanism isdisengaged (whether there be a centrifugal clutch or a declutchingbrought about by loosening of the belt tension), the cutter blade cancontinue to rotate for a substantial time. This is because the onlymechanism which operates to slow the cutter blade is either the inertiaof the clutch part or the friction of the loosened belt. For this reasona separate brake arrangement is necessary if safe operation andcompliance with short stopping times are to be achieved.

It is the object of the present invention to substantially overcome orameliorate some of the above mentioned disadvantages and problems by theprovision of a powered lawn edger which is steerable with both hands,able to be manoeuvred in substantially the same fashion as a wheelbarrow, and able to be operated without tiring the operator. Thereforethe edger has a negligible turning circle, is able to be tilted easilyto either side and yet supports a substantial part of the weight of thepowered device. In addition, the arrangement should enable weight (ordownward force) to be concentrated at the cutter blade so as to improvestability.

In accordance with a first aspect of the present invention there isdisclosed a powered lawn edger steerable by an operator with both handsin the manner of a wheelbarrow, said edger comprising:

an elongate frame having handle means adjacent one end thereof and aground engaging wheel means having an axis of rotation adjacent theother end, said frame having a longitudinal axis;

a power unit located in front of the operator and carried by said frameintermediate said ground engaging wheel means and said handle means;

an enclosed power train interconnecting said power unit and a rotatablecutting device to rotate said rotatable cutting device, said rotatablecutting device being mounted for rotation in a substantially verticalplane in use, and being mounted adjacent said other end of said framewith its axis of rotation forward of said ground engaging wheel meansaxis of rotation;

said handle means comprising a pair of spaced apart handle grips;

said edger having a center of gravity which, in use, lies in asubstantially vertical plane passing through said ground engaging wheelmeans, and said center of gravity also being intermediate said handlemeans and said ground engaging wheel means, whereby said handle gripscan be manipulated to twist said frame about its longitudinal axis tolaterally tilt said cutting device from said vertical plane of rotation.

In accordance with a second aspect of the present invention there isdisclosed in a powered lawn edger having a frame, at least one groundengaging wheel means supporting the frame, a power unit carried by theframe, a cutting device rotatable by said power unit and heightadjustment means to adjust the height of said cutting device relative tothe ground, the improvement comprising a debris deflector carried withsaid wheel means, the height of said debris deflector relative to theground being unchanged with operation of said height adjustment means.

In accordance with a third aspect of the present invention there isdisclosed in a powered lawn edger having a frame, at least one groundengaging wheel means supporting said frame, a power unit carried by saidframe, a throttle means to increase or decrease the speed of operationof said power unit, and a cutting device rotatable by said power unit,the improvement comprising a throttle interlock mechanism wherein saidthrottle is operable to increase the speed of said power unit above anidle speed only on immediately prior operation of said interlockmechanism.

In accordance with a fourth aspect of the present invention there isdisclosed in a powered lawn edger having a frame, at least one groundengaging wheel means supporting the frame, a power unit carried by theframe, a cutting device rotatable by said power unit, and a transmissioninterconnecting said power unit and cutting device, the improvementcomprising a gear reduction means included in said transmission andhaving a gear ratio in the range of from 1.5:1 to 8:1.

In accordance with a fifth aspect of the present invention there isdisclosed a method of edging lawn alongside a formed edge of a path orroadway utilizing the edger of the first aspect, said method comprisingthe steps of:

energising said power unit to rotate said cutting device,

holding said handle grips one in each of a corresponding hand,

walking along said path or roadway whilst wheeling said ground engagingwheel means thereover,

steering said edger as necessary to align or maintain aligned, saidrotating cutter blade with the desired line of cut, and

twisting said edger about the longitudinal axis of said elongate frameby adjusting the height of said handle grips relative to said formededge as necessary to adjust the desired angle of cut.

A preferred embodiment of the present invention will first be describedand then a number of variations to that preferred embodiment will bedescribed, the description being with reference to the accompanyingdrawings in which:

FIG. 1 is a front perspective view of the left hand side of the handsteerable powered edger of the preferred embodiment,

FIG. 2 is a front perspective view of the right hand side of the edgerof FIG. 1 in use,

FIG. 3 is a schematic plan view of the edger of FIGS. 1 and 2 in use,

FIG. 4 is a side view of the edger of FIGS. 1-3 in a stable non useposition,

FIG. 5 is an exploded perspective view showing a substantially vibrationfree mounting for the handles,

FIG. 6 is a cross-sectional view through the clutch mechanism along theline VI--VI of FIG. 4,

FIG. 7 is an end view of the clutch mechanism in the direction of arrowVII in FIG. 6,

FIG. 8 is a longitudinal cross-sectional view through the throttlecontrol,

FIG. 9 is a side view of the throttle control but looking in theopposite direction to the view of FIG. 8,

FIGS. 10-14 are schematic end elevations of the device of FIGS. 1-4 inuse,

FIGS. 15-17 illustrate three further embodiments having differinghandles, and

FIGS. 18-20 illustrate three different ground engaging wheelconfigurations.

As seen in FIGS. 1 and 2, the edger 1 of the preferred embodiment takesthe form of a slender wheel barrow like device having a single groundengaging wheel 2 of appreciable diameter, a pair of handle bars orhandles 3 with hand grips 20 and a power unit or motor 4, all arrangedabout a generally elongate narrow frame 5. The wheel 2 has asufficiently large diameter to enable the edger 1 to be easily rolledlike a wheelbarrow including rolling over steps, rough terrain, lawn,tangled grass, garden bed peripheries, etc. The wheel 2 is below theelongated frame 5 and preferably (as illustrated in FIG. 3) on, or closeto, the longitudinal center line of the edger 1.

The motor 4 can be either an electric motor or any type of internalcombustion engine. The motor 4 is positioned in front of the operatorand is mounted at the head of the transmission frame 5 and is generallyprovided with a conventional speed dependent centrifugal clutch 57(illustrated in FIG. 6). A drive shaft 56 (also illustrated in FIG. 6)passes through the hollow stem 6 of the frame 5 to a ninety degreereduction gear box 7.

The frame 5 also has two wedge shaped receptors 8 to which the handlebars 3 are releasably secured by means of a releasable handle 9. Theframe 5 and handles 3 have a generally Y-shaped configuration. Thehandles 3 are preferably detachable so as to place the edger in atransport or storage configuration having a reduced overall length. Theentire edger 1 is able to be easily placed in the boot or trunk of evena small motor vehicle.

Extending from the outer housing of the gear box 7 is a pivoted arm 11(FIG. 2) on the free end of which the wheel 2 is rotatably mounted. Thearm 11 is pivotal by means of a resilient height adjustment handle 12which is biased so as to be able to be set by the operator and retainedin a position setting in any one of a number of positions relative to aheight setting plate 13 which includes a number of apertures.

Extending from the gear box 7 is a shaft 16 (FIG. 1) which carries anactuator in the form of a single cutter blade 17 which is shielded by aguard 18. On the leading end of the guard 18 is mounted a foresight 19.The cutter blade 17 and shaft 16 are a fixed distance from the engine 4.

The gear box 7 provides a gear reduction (between 1.5:1 and upto about8:1) but preferably around 4:1 with an engine of, say, 30 cc capacity.Because of the low gear ratio the peripheral speed at the tips of thecutter blade 17 is kept low, even at engine speeds of upto 10,000 rpm ifusing, say, a 20 cc capacity engine. If a large capacity engine of, say,50 cc capacity-is utilised, then that engine has more power andtherefore can rotate the large blade 17 at slower engine speeds using agear ratio in the vicinity of, say, 2:1 or even 1.5:1.

Because of the slower blade peripheral speed, a longer blade 17, whichtakes a longer time to wear out, is able to be used. The blade 17 islonger than those blades used on heavy duty carriage edgers, and iscertainly much longer than the short blades used on light duty wheeledbrush cutter type edgers and the light duty wheeled carriage class ofedgers. A longer blade 17 also has the advantage of "pulling" thelightweight edger 1 along and thus makes the edger 1 self propelling tosome extent at least.

It will be apparent to those skilled in the art that the handle 12 andplate 13 permit the height above the ground of the blade 17 to beadjusted for any given angle of inclination of the transmission frame 5relative to the ground by the raising or lowering of the gear box 7.Thus, although the operator is able to raise or lower the handles 3 andthereby tilt the transmission frame 5 in a small arc within a verticalplane about the point of engagement of the wheel 2 with the ground, thisadjustment is small. The fundamental height setting is adjusted by theheight adjustment mechanism in the form of the arm 11, handle 12 andplate 13. This enables the height to be set by each operator. Thissetting is used to determine the depth of cut by the blade 17 into thelawn and/or soil surface. This adjustment also allows for compensationfor the shorter length of a worn blade 17 and/or the different heightsand/or arm lengths of different operators. Also the step-by-step heightadjustment cannot change during use as do sliding adjustments which relyupon friction to clamp the slide in position.

In addition, the extended stub axle 10 carried on the free end of thearm 11, and about which the wheel 2 rotates, carries a debris deflector15. Unlike the cutter guard 18 which is raised or lowered with theheight adjustment mechanism 12 and 13, the debris deflector 15 remainsat a constant height relative to the ground surface. Preferably thedebris deflector 15 is rigid and is able to pivot about the axle 10 (forexample to swing over lumps of tangled grass) and hangs down in theposition illustrated in FIG. 1 under the influence of its own weight.The lower edge of the debris deflector 15 reaches ground level, or nearto ground level. If desired, a spring (or equivalent conventionalmechanism not illustrated) can be used to urge the deflector 15 backinto its substantially vertical rest position. Thus the debris deflector15 is always at a constant height and/or position relative to the groundsurface, regardless of the height adjustment set by the handle 12. Thisis to be contrasted with prior art rubber flaps which hang from guardsfor cutter blades and thus move with the height adjustment mechanismbeing raised, or drag severely on the ground when lowered. The debrisdeflector 15 functions to protect the operator from flying stones ordebris that can pass below the cutter blade guard 18 as the cutter bladerotates in the direction of arrow A in FIG. 1. Alternatively a flexibledebris deflector flap can be used, with one end of the flap affixed inany conventional way to the wheel stub axle 10.

Both the debris deflector 15 and guard 18 stop the ascent of dust, grit,grass cuttings and other flying debris thrown up by the cutter blade 17.As a consequence, the operation of the edger 1 is not only rendered moresafe for the operator, but dust is less likely to enter into the engineor motor 4 thereby prolonging engine life.

As indicated in FIG. 1, the engine 4 has a throttle control 21 and, ifdesired, a brake 14 which is connected via a cable to the engine 4. Thebrake 14 is released by grasping the brake lever 26 against thecorresponding handle grip 20.

Turning now to FIG. 5, the detail of an anti-vibration mounting for thehandles 3 is illustrated. The stem 6 is provided with two mouldedplastic wedge shaped receptors 8. A steel skin 51 is positioned betweeneach receptor 8 and a corresponding U-shaped rubber channel 52 intowhich the handles 3 are recevied. A rubber sleeve 53 passes through thestem 6, receptors 8 and skins 51. A bolt 54 passes through the handles3, channels 52, skins 51 and sleeve 53 and is able to function as aclamp by tightening of handle 9 into which the bolt 54 is received.

As also seen in both FIG. 5 and 6, the upper end of the stem 6 carries abearing 55 for a, preferably solid, transmission shaft 56 whichinterconnects a centrifugal clutch 57 with the gear box 7 (FIG. 2). Theclutch 57 has a substantially conventional pair of spring loaded shoes58 (FIG. 7) which under the influence of centrifugal force when rotatingengage the clutch drum 59. This engagement transmits power from theengine 4 to the shaft 56. Preferably a brake 14 in the form of a brakeband 61 which extends around the clutch drum 59, is provided. The brakeband 61 is connected to the brake lever 26 (FIG. 1) by means of a cable64.

The brake 14 is biassed on by means of a spring 65 which pulls the brakeband 61 into engagement with the exterior of the clutch drum 59. Thebrake 14 is released by grasping the brake lever 26 against the adjacenthandle grip 20. This pulls the cable 64 against the spring 65 therebyfreeing the brake band 61 as illustrated in FIGS. 6 and 7.

The details of the throttle control (which is right handed) areillustrated in FIGS. 8 and 9. The throttle of the engine is controlledby a cable 70 which is able to be pulled by rotating a throttle trigger71 clockwise as seen in FIG. 8. The idle speed is controlled by settingscrew 72.

However, before the throttle trigger can be moved to increase enginespeed above idling, an interlock lever 74 must be momentarily moved inan anticlockwise direction as seen in FIG. 8. This movement is broughtabout by the operator's right thumb which engages the free end 75 of theinterlock lever 74.

The interlock lever 74 is provided with a lug 76 which, in the restposition of the interlock lever 75, engages a similar protrusion 77 onthe throttle trigger 71, thereby preventing movement of the throttletrigger 71. As a consequence, the operator must first depress theinterlock lever 75 with his right thumb before being able to pivot thethrottle trigger with his right index finger. Once the throttle triggermoves away from its idle position, a return spring 78 resets theinterlock lever 74 into its initial position. This is the positionillustrated in FIG. 9. Thus the trigger 71 can be moved to increase ordecrease engine speed so long as the engine 4 is not idled. If thetrigger 71 is returned to the idle position, then the lug 76 andprotrusion 77 are re-engaged. As a result, the engine speed cannot beincreased again without the interlock lever 74 being depressed. Thethrottle control 21 also has a stirrup guard 79 to prevent the trigger71 being bumped whilst the engine 4 is operating. Clearly, for a lefthand throttle, the interlock lever 74 should be placed on the oppositeside of the throttle trigger 71 so as to be accessible by the leftthumb.

It will be apparent to those skilled in the art from FIGS. 2 and 3, inparticular, that the edger 1 of the preferred embodiment is mechanicallysimilar to a slender wheel barrow, in that the center of gravity of theedger 1 is positioned in a substantially vertical plane located betweenthe handles 3, and is also positioned between the wheel 2 and thehandles 3. As a consequence of this arrangement, the greater part of theweight of the edger 1 is borne by the wheel 2 and only a small part issupported by the operator. In addition, in operation the edger 1 issubjected to forces at only three locations, the wheel 2 and bothhandles 3. This makes for a very stable arrangement.

Furthermore, because the shaft of the cutter blade 17 is a very shortradial distance from the shaft of the wheel, even though the edger 1 islight in terms of its overall weight, the leverage between the cutterblade 17 and the wheel 2 is very substantial. This prevents blade bounceand furthermore improves the stability of the edger 1 in operation.

However, the edger 1 of the preferred embodiment differs from aconventional wheelbarrow in relation to the position of the center ofgravity relative to the frame of the edger. In a conventionalwheelbarrow, especially one carrying a heavy load such as wet concrete,the center of gravity is above the frame. Thus if one handle is lowered,and/or the other raised, an inherently unstable position is quicklyreached and the operator may be unable to prevent the load spilling outsideways as the wheelbarrow rotates about its longitudinal axis.

This is to be contrasted with the above described embodiment, where thecenter of gravity (determined to a certain extent by the position of theengine 4) lies on, or close to, the longitudinal axis of the frame 5.This has the result that the mass is basically concentrated along thelongitudinal axis of the frame and only the handles diverge from thisaxis to any considerable extent. Thus the handle grips 20 can becomfortably moved laterally in a fully controlled arc about thelongitudinal axis of the frame 5 without the edger 1 becoming unstablein any way. This makes for particularly easy tilting of the edger 1 inorder to quickly and precisely tilt the cutter blade 17 into any desiredcutting angle by any operator and without any difficulty.

Because of the slender wheelbarrow-like configuration of the edger 1,like a wheel barrow the edger 1 has no minimum turning circle and can beturned through 360° on a spot. The edger 1 can also be steered by movingthe handles 3 to left or right about a vertical axis passing through thewheel 2. In operation, by lifting one of the handles 3 and/or loweringthe other handle, the handles 3 are thereby easily twisted about thelongitudinal axis of the stem 6. This lateral tilting or twisting actionthrough a short arc moves the plane in which the cutter blade 17 rotatesfrom the vertical as indicated by the arrows B in FIG. 1. This movementis able to be achieved quickly and easily by the operator in response tochanging conditions, any obstacle, etc. The closer the blade 17 to thelongitudinal axis of the edger, the easier the movement of the handlegrips 20 in order to achieve a given effective tilt of the cutter blade17.

As indicated in FIGS. 2 and 3, as the operator normally is positioneddirectly behind the edger 1 (indicated as position G in FIG. 3), andoperates by walking in a natural stance forward along the line of cutindicated by arrows C in FIGS. 1 and 3. This natural stance enables theoperator to work for long periods without tiring. Since the operator isnot stooped, and has a straight back, the operator can work without fearthat serious back injury may eventually occur.

It will be apparent to those skilled in the art that as the operatorwalks along in a straight line path, the plane in which the cutter blade17 rotates lies within the distance between the shoulders of theoperator as the operator moves along the path C. Considered another way,each shoulder of the operator thus traces out a locus or path indicatedby arrows D in FIG. 3 to either side of the cutter blade 17.

From FIG. 2 it is also apparent to those skilled in the art, that thecutter blade 17 and guard 18, being located close to the ground, can beextended underneath low lying bushes without difficulty and withoutother parts of the edger 1 striking the bushes.

Also because the edger 1 is light and well balanced, the operator can becomfortably positioned to either side of both handles for any reason,for example, to allow the edger to edge under overhanging bushes ortrees where a directly following operator cannot follow. Alternatively,the operator being positioned to one side (or the other) of the handlesis able to manoeuvre the edger around the perimeter of small irregularshaped flower beds, or to side step around obstacles such as a smallbush, water tap, garden hose reel, mud puddle, or any other obstacle.

Therefore it is not necessary for the operator to always be positioneddirectly behind the edger, even if the edger moves along the straight"line of cut" C. Thus the operator can easily and quickly "side step"from one extreme on one side of both handles (position H in FIG. 3)through to the other extreme on the other side of both handles (positionJ in FIG. 3). This change in operator position can be carried outwherever it is necessary without altering or adjusting hand positions ofthe operator. That is, the position of the arms and body changesrelative to the substantially unchanged position of the hands and edger.Thus the operator retains a full and comfortable control of the edger atall times.

Conversely, the "foot prints" marked H and J in FIG. 3 can alsoillustrate either one of two new positions into which an operator canmove and also move the edger so that it resumes its position directly infront of the operator. This change in position naturally results in achange in direction of the "line of cut" C.

This unique separate and/or combined operator/edger flexibility can becarried out without any strain or bother to the operator and withouttiring the operator.

The narrow profile of the front of the edger 1 also allows same to workinto narrow confines of space, for example where a post or otherstructure is positioned close to a curb or path. This is impossible fortypical 3 (or 4) wheeled carriage type edgers or prior art singlewheeled carriage devices.

Further, as best appreciated from FIG. 3, the foresight 19 enables theoperator to accurately guide the edger along the edge of the curb orpath.

If the motor 4 is an internal combustion engine, then in order to startthe engine, the handles 3 (or handle grips 20 if provided) can be restedon the ground as illustrated in FIG. 4. As a consequence, the edger 1 ispositioned in a very stable and secure position, coming into contactwith the ground only in three positions, namely the tips of each of thehandles 3 (or handle grips 20) and the bottom of the wheel 2. In thisposition the cutter blade 17 is clear of the ground.

With the edger 1 in this stable position, the operator is able to pullthe starting cord of the internal combustion engine 4 whilst being wellaway from the cutter blade 17 but adjacent the throttle control 21. As aconsequence, if not braked against rotation as explained above, anyspinning of the cutter blade 17 which may occur because of higherrevolutions of the internal combustion engine at the time of starting,occurs with the operator safely positioned well away from the rotatingcutter blade 17. After starting, the engine is idled and the automaticcentrifugal clutch 57 then disengages the cutter blade 17 from theengine 4. The throttle trigger guard 79 prevents the throttle control 21being inadvertently depressed by coming into contact with a bump orother object above the ground during starting.

The throttle trigger 71 also has a safety interlock as explained abovein relation to FIGS. 8 and 9, so that on idling, any accidental movementof the throttle trigger cannot occur, an operator's hand has to beholding the mechanism to operate same.

Of course, if the motor 4 is an electric motor, the throttle triggerwith safety interlock then controls an electric on-off switch inside themotor housing and can be easily manipulated in the operating position.An electric motor can be either a mains operated AC or DC motor or abattery pack operated DC motor.

As an alternative to the preferred two handles 3 resting on the ground,a ground contacting leg stand (not illustrated), either fixed orretractable, can also be used when the edger 1 is at rest.

It is especially desirable for electric motors that the above describedbrake 14 be provided. This is because internal combustion engines havecompression which quickly slows same after the throttle is released orreturned to idle. However, electric motors have substantial inertia andno equivalent braking action. For this reason they continue to rotatefor much longer periods of time after the power is switched off. Forthis reason the brake 14 is very desirable for electric motors. Onrelease of the brake lever 26 by the operator, for any reason, the brakeband 61 locks tight around the clutch drum 59 causing the blade 17 toquickly stop rotating.

A preferred feature which enables the expense of the brake 14 and allits associated components to be eliminated arises out of the combinationof an internal combustion engine 4, centrifugal clutch 57 and gear box7. This arises as follows. The internal combustion engine 4 itselfquickly stops rotating if the throttle is released or returned to idlebecause of the compression of the engine 4. This means that the clutchshoes 58 quickly retract leaving the clutch drum 59 to free wheel.However, since the clutch drum 59 and shaft 56 are connected to thecutter blade 17 via the gear box 7, all these items rotate together.

Because of the gear ratio (1.5:1 to 8:1) between the cutter blade 17 andclutch drum 59 the inertia of the cutter blade 17 acts to drive via thegear box 7, the shaft 56 and clutch drum 59. In this way the rotationalenergy of the cutter blade 17 is quickly dissipated and the cutter blade17 quickly stops rotating.

This result arises because of the frictional losses in the overalltransmission and because of the inertia of the shaft, gears and clutchdrum. Since these three items must be rotated at a higher speed than thecutter blade 17 because of the gear ratio, and the driving force is themomentum of the cutter blade 17, the cutter blade 17 quickly stopsrotating. Practical experiments with a gear box having a less than 4:1reduction, indicate that a 30 cc two-stroke engine running at full speed(7,500 rpm) will result in the cutter blade ceasing rotation inapproximately 2.5 seconds after the engine throttle is released by theoperator. This is well within the 3 second period specified in somejurisdictions and within which the blades of rotory lawnmowers must stoprotating. The regulations, or prespective regulations, can still becomplied-with but the expense of the brake is eliminated since thearrangement is inherently self-braking.

Irrespective of whether a brake for the cutter blade 17 is provided ornot, the operation of the edger 1 is as follows. With the engine idling,the operator lifts both handles 3 in order to hold same with the armsrelatively straight and extending directly towards the ground asillustrated in FIG. 2. The throttle control 21 can then be actuated toincrease engine speed. The edger 1 is then wheeled along the pathindicated by arrows C in FIGS. 1 and 3 to commence the edging operation.It will be apparent from FIG. 3, in particular, that the cutter blade 17is located in a plane which passes between the handles 3 and that theoperator walks along a trodden path or line which passes substantiallyover the "line of cut" unless the edger 1 is deliberately tilted orlongitudinally turned to alter course.

Several of the operational advantages of the edger 1 of the preferredembodiment are illustrated with respect to FIGS. 10-14. In FIG. 10, theedger 1 is being used to edge the lawn 22 growing at the left side of apath 23. As indicated in FIG. 10 the wheel 2 is moved along the leftedge of the path 23 adjacent the lawn 22 and the rotating cutter blade17 provides the necessary edging action. The first advantage is that thecutter blade 17 can be easily and quickly tilted out of a vertical planeby twisting the frame about its longitudinal axis in order to provide atilted cut, an adjustment to the cutting action, to miss any obstacle,to provide a closer or more distant cut, and so on.

FIG. 11 illustrates a second advantage able to be obtained by the edger1 of the preferred embodiment over a conventional carriage supportedlawn edger. Here the wheel 2 is being easily moved along the upper edgeof a formed concrete curb 24 of a gutter at the edge of a road 25. Againthe cutter blade 17 edges the lawn 22. However, the prior art carriagedevices are unable to be wheeled along the top of the curb 24 since thethree (or four) wheels cannot be accommodated on the narrow uppersurface of the curb 24 because of the side to side spacing between thewheels. This problem also occurs with the prior art single wheelcarriage devices due to their cutters being located a substantialsideways distance from the wheel, generally on an outrigger device ofsome kind. Such carriages (irrespective of whether they have single ormultiple wheels) can only be pushed (in the opposite direction) alongthe relatively rough grass. This is an onerous task-especially when longdistances are involved such as arises with the edging of nature stripsor verges alongside roads.

FIG. 12 illustrates an analogous situation to that of FIG. 11, butillustrates the procedure where the lawn 22 slopes towards the curb 24.Under these circumstances, the wheel 2 can again be accommodated on thenarrow top of the curb 24. However, with the prior art carriage deviceshaving to be wheeled on the grass, the grass slope of the lawn 22 wouldhave the effect of tilting the entire apparatus and therefore moving thecutting device of that prior art apparatus out of the vertical plane toa substantial extent. Also when pushing forward such a prior artcarriage edger, the carriage tends to continuously slide down the slopeand this tendency has to be continually resisted by the operatorproviding an upward force component. This is both tiring as the operatorhas to adopt a "crab-like" or twisting motion and possibly walk in thegutter where parked vehicles can obstruct his path. It is also verydangerous as on a busy suburban road with moving traffic close to thecurb, the operator runs a substantial risk of being struck by a passingvehicle.

As seen in FIG. 13, the edger can be operated so as to edge grass orlawn 22 growing up against a vertical surface such as a wall 26. Here bylaterally tilting the handles 3 and therefore the wheel 2, the cutterblade 17 is easily moved out of a vertical plane and so bothsimultaneously inclined and brought to bear adjacent the base of thewall 28 with a fast, simple, comfortable and easy movement requiring nophysical effort. This is much more convenient when compared with theslower and more difficult blade tilting arrangement on those edgers thathave a swivel arrangement for blade tilting arrangement.

In FIG. 14 the use of the edger 1 to trim the side of a garden bed 27(or golf bunker) is illustrated. Here the wheel 2 rolls over therelatively rough lawn 22 with ease whilst the cutter blade 17 cuts thedesired edge to a level well below the grass surface. The wheel 2 isable to follow any irregularity in the ground surface in a way which acarriage device of three (or four) wheels cannot replicate since thecarriage effectively "averages" the position of all wheels and thus"bounces" over irregularities.

It will be appreciated by those skilled in the art that theconfiguration of the edger 1 is inherently safe. In the event that theoperator should stumble, the safety brake 14 and/or throttle control 21is/are released, so the centrifugal clutch 57 disengages the cutterblade 17. This enables the edger 1 to roll forward and the handles 3 todrop to the ground. The safety interlock 74 on the throttle trigger 71ensures that the throttle cannot be re-accelerated. This is a relativelysafe situation with the cutter blade 17 safely raising out of, andabove, the ground while it is quickly stopped and without thepossibility of the blade dislodging debris towards the operator, orpossibly dragging the apparatus forward against some other object orperson etc.

Similarly, if the operator should fall over rearwardly for some reasonsuch as tripping or slipping, then because the cutter blade 17 is thepart furthest from the operator, and also because the wheel 2 is betweenthe operator and the cutter blade 17, any rearward movement of the edger1 is blocked by the wheel 2 coming into contact with the operator beforethe cutter blade 17 can strike the operator.

Turning now to FIG. 15, an alternative form of frame and handle 30 isillustrated. Rather than a Y-shaped frame 5 with two separate handles 3as in FIGS. 1-4, in the embodiment of FIG. 15 the frame 35 is generallyT-shaped and the handle 30 takes the form of a generally rectangularstructure which is both of adjustable length and pivotable in thedirection indicated by arrows E by movement of the cross member 33relative to the stem 6.

FIG. 15 also illustrates a forward facing flashing or blinking light 38.The light 38 can be energised via either a battery (not illustrated) orthe magneto of the engine 4. The light 38 is arranged to flash on andoff automatically whilst the engine is operating. This assists in thesafety of those government employees on busy and/or narrow roads.

Similarly, FIG. 16 illustrates another embodiment in which the motor 40is mounted adjacent the wheel 2 but with its center of gravity eitherabove the wheel 2 or towards the handles 43 but close to the wheel 2. Inthis configuration less of the weight of the motor 40 is carried by theoperator but the center of gravity of the edger 1 as a whole stillremains located not only substantially centrally between the handles 43so as to be in line with the wheel 2, but also between the wheel 2 andthe handles 43. However, the motor 40 is closer to any dust generated bythe lawn edge trimming. As a consequence, this configuration does nothave the dust reducing advantage of the configuration of FIG. 1, andgenerally requires that an additional air filter be used for an internalcombustion engine. However, this configuration can be of advantage wherean electric motor is used. It is also be possible to have a smalllightweight electric motor in front of the wheel 2, directly orindirectly connected to the blade 17, but the center of gravity is stillbetween the wheel 2 and handle grips 20 because of the length of thestem 46 and handles 43.

Also illustrated in FIG. 16 is an alternative U or C-shaped arrangementfor the handles 43. Also in this embodiment an alternative stem 46 isprovided which is adjustable in length. The handles 43 are adjustable inheight. As indicated in FIG. 16, either a pair of handles 43 can beutilised, or a single handle 50 in the form of a hollow, substantiallyrectangular frame (as illustrated by broken lines). In a furthervariation, only one of the handles 43 can be provided but extended atthe top to allow both handle grips 20 to be present. This is therefore adifferent C-shaped arrangement. In FIG. 17 a generally T-shaped handlestem 36 is illustrated. If desired, this can be made with a singlerather than a dual stem.

In order to better edge in some difficult terrains such as a moderatelysteep grassed slope leading upto a retaining wall or fence, modifiedwheel arrangements can be advantageous. For example, as illustrated inFIG. 18 the wheel 2 can be provided with a pair of outrigger wheels 80one to either side in the manner of "training wheels" used by youngcyclists. Only one of the outrigger wheels 80 is illustrated in FIG. 18.Alternatively, as illustrated in FIG. 19, two narrow wheels 82side-by-side but spaced slightly apart on the same axle can be usedinstead of wheel 2 to give improved "biting in" of the narrow wheel rimsinto soft soil on steeply sloping grass surfaces. Thirdly, asillustrated in FIG. 20, two in-line wheels 83 with a narrow gap betweentheir co-planar rims can be used since these follow the intended routebut provide additional traction.

The foregoing describes only some embodiments of the present inventionand modifications, obvious to those skilled in the art, can be madethereto without departing from the scope of the present invention. Forexample, the cutter blade 17 can be replaced by a cutter disc or a nylonlike filament. In addition, although the device of the present inventionhas been described in relation to lawn edging, the device also findsapplication in aerating lawns. In this application, a series of groovesare cut in a lawn in a criss-cross or cross-hatched pattern in order toprovide the aeration effect.

Various modifications can be made to the present invention withoutdeparting from the apparent scope hereof.

We claim:
 1. A powered lawn edger steerable by a walking operator in themanner of a wheelbarrow, the edger comprising:a. an elongated framehaving handle means attached thereto adjacent one end thereof and havinga ground engaging wheel means attached thereto adjacent the other endthereof, said ground engaging wheel means being below said frame withsubstantially the entire ground engaging wheel means lying below saidframe; b. a cutting device mounted adjacent said other end of said frameforward of said ground engaging wheel means, said cutting device beingrotatable about a horizontal axis; c. height adjustment means connectedto said frame for increasing the height or decreasing the height of saidframe relative to the ground; d. a power unit mounted on said frame; e.an enclosed power train interconnecting said power unit and said cuttingdevice for rotating said cutting device; and f. said ground engagingwheel means, said cutting device, said power unit, and said power trainbeing positioned on said frame such that the center of gravity of theentire edger, in use, lies within a substantially vertical planeintermediate said ground engaging wheel means and said handle means andpassing through said ground engaging wheel means, whereby said handlemeans can be manipulated by the operator to twist said frame about alongitudinal axis to laterally tilt said cutting device from itsvertical plane of rotation.
 2. An edger as claimed in claim 1, whereinsaid height adjustment means comprises an adjustment handle resilientlybiased toward a setting plate, and wherein said adjustment handle andsaid setting plate are releasably engageable at a plurality of engagedpositions, the height being adjustable to any of a plurality ofpredetermined heights each corresponding to one of said plurality ofengaged positions.
 3. An edger as claimed in claim 1, including a debrisdeflector supported by an axle about which said ground engaging wheelmeans rotates, the height of said debris deflector relative to theground remaining unchanged with the operation of said height adjustmentmeans.
 4. An edger as claimed in claim 1, wherein said power trainincludes a transmission including gear reduction, wherein the gear ratiobetween said power unit and said cutting device is from 1.5:1 to 8:1. 5.An edger as claimed in claim 4, including a gear box having an outputshaft and an input shaft and wherein said cutting device is mounted onsaid output shaft of said gear box, said output shaft being at anyangle, preferably approximately 90°, relative to said gear box inputshaft, and said output shaft is a fixed distance from said power unit.6. An edger as claimed in claim 1, wherein said frame has a generallyY-shaped configuration.
 7. An edger as claimed in claim 1, wherein saidhandle means are generally C-shaped in configuration.
 8. An edger asclaimed in claim 1, wherein said handle means are adjustable relative tosaid frame.
 9. An edger as claimed in claim 1, wherein said power unithas a throttle means to control the speed thereof and said throttlemeans has an interlock mechanism wherein said throttle means is operableto increase the speed of said power unit above an idle speed only onimmediately prior operation of said interlock mechanism.
 10. An edger asclaimed in claim 9, wherein said throttle means comprises a pivotablethrottle trigger and said interlock mechanism comprises a pivotableinterlock lever which in a rest position blocks movement of saidthrottle trigger in a speed increasing direction, said interlock leverbeing pivotable out of its rest position to permit said throttle triggerto be moved in a speed increasing direction.
 11. An edger as claimed inclaim 10, wherein said throttle means includes a stirrup guard toprotect said throttle trigger.
 12. An edger as claimed in claim 1,wherein said ground engaging wheel means rotates in a plane of rotationwhich is substantially parallel to, and closely spaced from, a plane inwhich said rotatable cutting device rotates.
 13. An edger as claimed inclaim 1, wherein said handle means includes handlegrips positioned oneto either side of said plane of rotation of said cutting device.
 14. Anedger as claimed in claim 13, wherein said handlegrips are spaced apartby a distance greater than, or substantially equal to, the shoulder toshoulder spacing of said operator.
 15. An edger as claimed in claim 1,having vibration damping means located between said frame and saidhandle means.
 16. An edger as claimed in claim 1, including a brakemeans which when unactuated prevents rotation of said cutting device andwhich requires continuous actuation during operation to allow forrotation of said cutting device.
 17. An edger as claimed in claim 1,wherein said handle means are generally of T-shaped configuration. 18.An edger as claimed in claim 1, wherein said handle means are generallyof U-shaped configuration.
 19. An edger as claimed in claim 1, whereinsaid handle means comprise a hollow substantially rectangular frame. 20.A gasoline powered lawn edger comprising:a. a frame, at least one groundengaging wheel means supporting the frame; b. a power unit carried bythe frame; and, c. a cutting device rotatable by said power unit andheight adjustment means to adjust the height of said cutting devicerelative to the ground, the improvement comprising a ground touchingdebris deflector carried on an axle of said wheel means, the height ofsaid debris deflector relative to the ground being unchanged withoperation of said height adjustment means.